AP Bio Unit 2: Cell Structure and Function

Isometry is when cell structure retains their overarching shape but they increase in volume

Allometry is when the shape changes with the increase in volume/.

Surface area is 6s²

Volume is s³

Key Idea: The volume inside the cell gets bigger much faster that the surface area, outside of the cell. So the surface area changes shapes or accompany sie differences to balance the slower increases of SA to volume. In other word we add more surface area and so that helps the nutrients to move in and out easier.

• In the intestinal tracks: microvillli increases SA of small intestime and increase the volume.

Surface area increases the objects squares—→ x²

As volumes increases the objects cubes ——→ x³

Bacteria has a higher surface area to volume as they are smaller. This helps pass nutrients and wastes in and out of the cell quickly.

A larger or higher surface area is very beneficial because bacteria can exchange materials easily and causing them to grow.

Diffusion: It is the movement of molecules from high concentration to low concentration. So moving down the concentration gradient.

Diffusion is used by bacteria to primarily move matrieals through and out the cells. Bacterials have a higher surface area to volume ratio.

High Surface Area to volume—> smaller object. No help needed.

Lower SA to Larger Volume ——→ large object. Vesicle transport.

Diffusion keeps the bacteria small because bacteria relies on passive diffusion and that would get slow if traveling over large distanes and would causee to the downfall of the bacteria. So they have a larger SA when being small.

The ratio SA to V decides efficiency of absorbing nutrients.

Sponges: Move pass the limit by making their whole bodies as a water pumping systems. They use pores in which water travels. There aren’t any thick rings, and they are always directionally faced towrds the flowing of fresh water. So they move in the internal environment from pore to pore. The sponges can expand a lot.

Sea Jellies: They have bodies that are only few cells thick and so oxygen can pass easily throught them as its a very short distance.

    They have a hood, jellyfish, causes a increase in the Surface area enabling more directions for oxygen to flow through.

    Gastrovacular caivty: Meaning that there is a cavity inside them that has seawater in them in which oxygen flows inside and outside of the cavity.

Humans: Have a respiratory system. The lungs deal with the oxygen and carbon dioxide.

Bulk Flow: Bulk Flow is the movement of large fluid or gas due to pressure differences.

Bulk Flow can be seen when air pushes in to our lungs and when blood caries the oxygen, oxygen flows into the cells.

Bulk Flow: CO2 and Glucose.

The diaphragm expansion when air comes in and relaxes when you breathe out. It controls your breathing.

Bulk flow in olants helps carry the water and oxygen to the xylem. Allows it to travel long distances.

Diffusion is when a movement from high concentration to low concentration happns w/out ATP.

Important stuff in cell membrane,

Phospholipid.

Cholesterol

Proteins.

Carbohydrates

A phospholipd has a head which is hydrophilic( polar). A tail which is hydrophobic(non-polar).

You can see a phospholipd bilayer in a plasma membrane, nucleus envelope , golgi apparatus, mitochondria, endoplasmic reticulum.

Liposome is a spherical structure that is covered in phospholipid bilayer. They create enclosed environment to carry water soluble or fat soluble things inside the body.. In water the heads face the water while the tails are facing away.

• Phospholipds can move laterally.

• Membrane proteins are moving.

• Membrane proteins can join or seperate.

Van der Waals ( a weak interaction between the hydrophobic tails) holds them in place to make it stable.

Longer fatty acids tails——> less fluid

More van der Waals interactions——> less fluid.

More saturated fatty acids———→ less fluid

More unsaturated fatty acids ——————→ more fluid

Higher temp—————→ more fluid

Cholesterol at low temp—————→ more fluid ( Cholesterol is a temperature buffer, so it stop low temperatures to have low fluid, it create more fluid.

Cholesterol at high temp ———————> less fluid( Cholesterol is temp buffer, so it stops from more fluid and gives less fluid).

Rarely do the heads flip-flop. It can if theres an enzyme or special event.

Cell membrane isn’t rigid, so cells can pass through.

In the cell membranes there are proteins.

Transport proteins- carry stuff in and out of the cell.

Receptor proteins- allow cells to recieve signals from the environment.

Electron transport chain- Proteins pass electrons to harness energy for the cell. ( They literally pass)

Anchoring Proteins- Some attach to other proteins( anchor themselves) to help maintain cell structure and shape.

Two groups:

Integral vs pheripheral.

Integral include the transmembrane proteins that spans the entire membrane. Trans mean across. So across the membrane.

Pheripheral Proteins- Near the cytoplasmic side of the extracellular membrane( Literally to the pheripery).

Transmembrne protein ( curly things)- Span the whole phospholipid bilayer. B barrel are bacteria, mitochondria and chloroplasts. A helical are in all cell membranes.

Hydrophobic region stabilizes

The transmembrane protein allows communication. The external side of hydrophilic region is the receptor and the interior side of the hydrophilic region is the transmitter and cell response side.

The pheripheral protein interacts with the phospholipid bilayer and integral membrane proteins by weak interactions such as hydrogen bonds and ionic interacctions.

Glycoproteins are proteins with many carbs attaches to it. Helps with adhesion( since it’s attached) nd communication.

Glycoproteins and Glycolipids are the macromoleules in the phospholipid bilayer.

Glycoproteins are attached to protein.

Glycolipids are when glycans( red) attached to lipid.

Fluid mosaic model is a model showing the fluid phospholipid bilayer. It is fluid wand proteisn move laterally.

The purple is a protein. The red is glycans.

Two ways proteins associate with membranes( physically attach).

• Transmembrane: bilayer, phobic regions are in the midd.e

• Peripheral - inner or outer, weak noncovalent bonds.

The model is saying that they are moving laterally. it is DYNAMIC.

Golgi- Fold and transport proteins.

Ribosomes are the ones that make proteins.

Rough ER helps with making and folding proteins, ribsomes studded, making cell membrane.

smooth ER- lipid synthesis, detoxification synthesis, carbohydrate metabolism, calcium storage.

Lysosomes are digestive, hydrolytic enzymes that recyle macrocmolecules and worn out organelles.

Thylakoids are the flattened sacs in the chloroplasts. Collect light and collection of them is called gava or gana.

The ridges or structure of the mitochoondria is helpful for increase surface area and then ATP.

Mitochondria is found in all eukaryotic cells and the chloroplasts are in plants and algae.

Cellular respirations is when they take glucose, and oxygen and break it down to release ATP or make ATP.

Sugars are made from Photosynthesis.

Cytoskeletons in eukaryotic cells: microtubles(thicker), microfillaments( thiner).

Turgor pressure: It’s pressure to the cells contents. Cell wall goes against this, causing the cell to burst. Pushing the plasma membrane to the cell wall. a hydrostatic force.

Plant walls are made of cellulose. Fungal cell of chitin. Bacterial chain are peptidoglycan. Algan cell is silica, celllulose, calcium carbonate.